It has become increasingly apparent that in vivo models are helpful for many areas of cancer research. To this end, UCLA has established a Nude/SCID Mouse Shared Resource that breeds and houses severe combined immunodeficient (SCID) mice, and provides housing for nude (athymic) and SCID mice for biomedical research. In this Shared Resource, investigators can introduce normal or transformed tissues of human or murine origin into immunodeficient mice that will not reject the implanted tissues. Consequently, experiments can be performed that provide insights into how these cells behave in vivo and address experimental therapeutic protocols. The services that this Shared Resource provide include: 1) providing SCID mice at reduced costs to investigators in the JCCC; 2) maintaining an appropriate working laboratory for biosafety level 2 (BSL-2) mouse experiments related to cancer, including appropriate housing for nude and SCID mice, surgical equipment and supplies; 3) providing an appropriate BSL-3 level animal facility for use with biohazardous agents relevant to cancer, such as oncogenic viruses; and 4) providing animal maintenance and technical assistance for in vivo experiments. This Shared Resource also provides expertise/consultation on animal experimentation and surgical techniques required for relevant in vivo experiments performed by investigators in the JCCC. Taken together, this Shared Resource provides a working environment and needed expertise that would not otherwise be readily available to individual investigators, and enhances studies of oncogenesis and therapeutic approaches to various malignancies.